There’s a lot of buzz in and around Congress right now about NASA’s proposed mission to capture an asteroid, which Republicans are disinclined to support.

The issue has gotten considerable news coverage because NASA is rarely a partisan issue. However, Republicans do not like NASA’s plans to send a robotic spacecraft to an as-yet unidentified asteroid and tow it into the vicinity of the moon, where humans can visit it.

Being the subject of congressional infighting, of course, does NASA no good. But this battle is a distraction from NASA’s real problem, which neither Democrats nor Republicans are willing to acknowledge. Namely, the space agency is being tasked with building a huge and powerful rocket it will not be able to afford to fly.

A couple of weeks ago a space enthusiast, John Strickland, analyzed the launch costs of NASA’s Space Launch System, which consists of a large rocket that could initially launch 70 tons into orbit and eventually 130 tons, and a space capsule, Orion.

For various, supportable reasons Strickland concludes that the SLS system would likely launch, on average, every four years, at a cost of more than $14 billion per launch. Here’s how the costs break down:

Total cost for a single launch of the SLS. (John Strickland/Space Review)

Further conclusions made by Strickland include: With these costs NASA would have virtually no funds available for base construction anywhere in space, at L1/L2 points, on the Moon, or on Mars. And NASA’s rocket is likely to cost as much as 15 times, per launch, as SpaceX’s Falcon Heavy rocket, which is projected to lift 60 tons to orbit.

In short, then, NASA’s rocket plan would appear to be unsustainable. Especially for an agency that, right now, is straining under the burden of budget sequestration.

“It’s definitely one of the biggest challenges that we face,” Ellen Ochoa, director of Johnson Space Center, told me this week. “We are in the midst of looking at everything we do at JSC, how we can do it more efficiently and more effectively. So we’re looking at all the various areas we work in, where we should invest and divest. It’s a big effort.”

Johnson Space Center is leading development of the Orion spacecraft, which will make an initial flight test in 2014, and conceivably could carry humans into space in about eight years.

An artist’s concept drawing of the SLS. (NASA)

Development of the SLS rocket is being done at Marshall Space Flight Center in Alabama. The Huntsville Times asked Dan Dumbacher, NASA Deputy Associate Administrator for Exploration Systems Development, about Strickland’s analysis.

“We have a tight budget to work with, that budget allows us to build the space launch system and Orion, and Orion will fly on SLS,” he said. ”Once we get SLS and Orion built, we have the foundational capabilities, two of the key elements that we need for human exploration beyond low-Earth orbit. Once we get those into operations phase, the budget wedge, so to speak, opens up, and that’s when we start to develop the next elements we need for exploration, be it habitats, landers, whatever’s needed for exploration. But because of the budget constraints, we have to do that step by step. The first step is SLS and Orion.”

One can sympathize with Dumbacher. He’s trying to do what his boss, NASA administrator Charlie Bolden, is telling him to do. And Bolden is being directed by President Obama and Congress, who continue to remain at odds over where NASA should fly, if it ever develops the capability to fly beyond low-Earth orbit.

But for goodness sake, someone needs to inject some reality into this discussion. If Strickland is right the SLS is prohibitively expensive, and given the historical track record of NASA’s rocket programs, has very little chance of surviving an eight- or 10-year development cycle. And if, by some miracle, it does get developed, it will be incredibly expensive to fly, leaving no money to develop the hardware to do something meaningful with humans in space.